Originally Posted by TejanoTrackie

Rear tire size: Formula (psi)

700x23C: 0.33 x rw + 53.33

700x25C: 0.33 x rw + 43.33

700x28C: 0.33 x rw + 33.33

700x32C: 0.17 x rw + 41.67

Where rw = rider weight

Front tire pressure = 0.9 x Rear tire pressure for the same tire size